Color filters prepared by laminating a coloring matter layer on an insulating substrate are used in a color liquid crystal panel for a display of a liquid crystal TV, a personal computer or the like. Heretofore, a color filter having a structure as indicated in FIG. 16, has been known. In the color filter as indicated in FIG. 16, a transparent ITO (Id-Sn oxide) electrode (b) is formed on an insulating glass substrate (a). On the ITO electrode, coloring matter layers (c) for primary three colors, i.e., R (red), G (green) and B (blue), are formed, and a black matrix (light-shielding film) (d) is formed between each of the coloring matter layers (C). Such black matrix is used to avoid lowering of contrast and color purity due to leaked light. In addition, in FIG. 16, (e) denotes a top coating layer and (f) denotes a post-ITO layer.
In general, the coloring matter layers of the color filters are formed by known methods. Such known methods include: a printing method which comprises printing inks for three primary colors (RGB) on a glass substrate with use of a printing equipment; a dispersion method which comprises applying a pigment dispersed in a UV-curable resist on a glass substrate, and then forming coloring matter layers for red, green and blue by repeating mask exposure and thermal curing, three times, by way of a photo-lithography method; a dyeing method which comprises forming a resist layer as a dye preventing layer on a gelatin layer, and dyeing the gelatin layer to form coloring matter layers for RGB; an electro-deposition method which comprises forming a dispersion of a pigment and an electrodepositing polymer, and subjecting the dispersion to electro-deposition treatment utilizing an electrode formed on the substrate; and a micellar disruption method which comprises forming a dispersion of a pigment and a surfactant, and subjecting the dispersion to electrolytic treatment utilizing an electrode formed on the substrate.
The coloring matter layers of the color filter as shown in FIG. 16 are usually formed by way of an electrical treatment such as an electro-deposition method or a micellar disruption method (Refer to Japanese Patent Application Unexamined Publication No. 63-243298).
Carbon type photo-resist materials are widely used in the other color filter production methods such as a printing method, dispersion method and dyeing method. However, if such carbon type photo-resist materials are used in the electrical treatment such as a micellar disruption method or an electro-deposition method, there will be several problems due to their conductivity. More specifically, if such a conductive resist material is used, when a black matrix is first formed and then coloring matter layers are formed, or when electrodes for forming coloring matter layers are used to drive liquid crystals, the vicinal transparent electrodes will be electrically connected through the black matrix. Thus, the operations cannot be properly conducted.
Accordingly, in a micellar disruption method or an electro-deposition method, as an insulating resist material used for forming a black matrix, the insulating material preferably having a surface resistance of not less than 10.sup.7 .OMEGA./cm.sup.2 is used.
As insulating resist material used for forming a black matrix, organic pigment type materials are known.
However, when a black matrix is prepared from an organic pigment type insulating resist material, there is a problem that the light-shielding rate is decreased. This is because a black matrix is formed by way of a photo-lithography method using a blend of three kinds of a resist material each containing a pigment for red, green or blue.
It is said that as for the light-shielding rate, for example, in the case of a TFT panel, optical density (OD) should be as high as 3.5 or more. However, in the case of an organic pigment type resist material, it is difficult to prepare a black matrix having an OD of at least 2.5.
It is desired that a metal black matrix is used as a black matrix having high light-shielding rate. However, in the case of using the metal black matrix in a micellar disruption method or an electro-deposition method, there will be the problem as is the same case with the above-mentioned carbon type resist due to conductivity of the metal black matrix. In other words, the micellar disruption method and the electro-deposition method cannot be used to form a coloring matter film. Also, a transparent electrode for forming a coloring matter film cannot be used to drive a liquid crystal.
Accordingly the first invention has its object to provide a color filter and its production process which solve the above-mentioned problems, i.e., having a structure wherein the vicinal transparent electrodes are not electrically connected even when a metal black matrix is used.
Further, the first invention has another object to provide a color liquid crystal panel and its driving method.
In the meanwhile, a printing method, a dispersion method and a dyeing method can form a coloring matter layer in a desired place on a glass substrate (e.g., effective display portion) because of their nature in the production process. However, when a color filter is formed by a micellar disruption method, an electro-deposition method or the like using electricity passing treatment as used in the first invention, the following procedure is needed. As shown in FIG. 17, it is necessary to form an electrode 6a for electricity passing treatment by taking out an electrode in a portion other than an effective display area S (non-effective display area) in order to connect a coloring matter layer forming transparent electrode 6 in the effective display area S to an outer electrode.
Further, as shown in FIGS. 17 and 18, it is required that the electricity passing treatment should be conducted for an electrode for the same color, at the same time, among stripe-shaped transparent electrodes for forming coloring matter layers arranged in the order of red, green and blue. To do this, the electrodes 6a for the electricity passing treatment for RGB should be formed such that each electrode 6a for each color should have different length; an insulating film is formed on an electrode taking out window frame 13; an electrode taking out window 14 is formed in the insulating film; then a silver paste 15 is applied along with the window for each color in the stripe-shape. Thus, the contact of the electrodes for each color is made.
Further, the present applicant provided in an earlier patent application (Japanese Patent Application No. 241084/89), a technique to simplify these steps. In such technique, when a black matrix is formed by using a light-shielding resist, an electrode taking out window is formed by using said resist.
However, in the above-mentioned conventional production process for producing a color filter, there is a problem that a step of applying a silver paste along with the electrode taking out window in the stripe-shape is required.
Further, when a liquid crystal display is assembled (cell assembling) by using a color filter, a step of removing the silver paste or a step of cutting or scrubbing the silver paste portion using a dicer or scrubber, is required.
Furthermore, there is a problem that additional equipments are required to remove dusts made at the time of removing the silver paste by vacuum treatment or the like.
Accordingly, the second invention has its object to provide a color filter, its production process, a color liquid crystal panel and its driving method, which can omit silver paste applying/removing steps, resulting in improvement of productivity.